This invention relates generally to fluid mixing devices and in particular to a proportioning device that mixes liquid detergent with a stream of water.
Fluid mixing devices for mixing a liquid detergent with a stream of water issuing from a water supply are well known and have been used for many years, particularly in conjunction with washing articles such as dishes in restaurants.
Such prior art devices typically make use of the venturi principle for inducing the liquid detergent into the water stream and two features are particularly desirable. One feature is the desirability of avoiding the problem of vacuum effect which can cause the backflow of the detergent/water mix upstream into the water supply. This is counteracted by providing an anti-syphoning air gap between the inlet nozzle and the venturi nozzle and using a special venturi nozzle design. An example of this type of device is shown in U.S. Pat. No. 3,166,086 owned by the assignee of the present invention. This arrangement functions effectively but may result in the discharge and overspill of the detergent/water mix through the air gap between the venturi nozzle and the inlet nozzle.
The other feature is the desireability of avoiding this overspill problem. U.S. Pat. No. 5,253,677 and U.S. Pat. No. 5,159,958 disclose approaches to the solution of the second problem by providing a splash plate upstream of the venturi nozzle, such as shown in both patents, and also the provision of barriers adjacent to the windows which provide the air gap. This solution requires additional parts which results in added complexity of manufacture of molded parts and the resulting expense.
The present proportioner solves these and other problems in a manner not disclosed in the known prior art.